San Francisco has been using ranked-choice voting since 2004. Here's how it works.

The Election Department is still processing about 42,000 ballots as of Saturday. The number is down from 64,900 on Friday and includes 28,000 vote-by-mail ballots and nearly 14,000 provisional ballots.

Elections officials said the provisional ballots will not be counted until next week.

The winner of the race will serve the remainder of the late Mayor Ed Lee's term, which runs through January 2020. Lee died unexpectedly in December.